Marantz DD-92 dead

Hi, just arrived.

I have just bought a non working DD-92.
All is working but no sound and bargraph display…
Changed capacitors (already leaked) but it shows FFFFFFFF, as before the capacxitor update.
The two segment before the Fs keep changing during the test, any clue about that?
I will test the head resistance and the path to the ICs for conductivity, what are the normal values for the heads resistance?
Any advices or tests I could try are welcomed.
I have electronics repair experience and a the tools needed.

Hi and welcome.

This video will give you some pointers.

Replacing the Head and PW03 Read-Write Board on a Digital Compact Cassette

Thank you.
I will test heads resistance values and ICs and I will report here.

Here are some measurements:

Resistances referenced to PIN 13 (GND) directly on the flat cable.

PIN 3 - AUX - 45,0 Ohm
PIN 5 - PB HEAD 0 - 44,6 Ohm
PIN 7 - PB HEAD 1 - 44,3 Ohm
PIN 9 - PB HEAD 2 - 44,1 Ohm
PIN 11 - PB HEAD 3 - 42,6 Ohm
PIN 15 - PB HEAD 4 - 45,1 Ohm
PIN 17 - PB HEAD 5 - 46,3 Ohm
PIN 19 - PB HEAD 6 - 46,5 Ohm
PIN 21 - PB HEAD 7 - 48,5 Ohm

The record heads have about 0.5-1 GOhm to pin 13. Are they gone or do I need to measure to another reference pin?

Anyone can help me with this:

“The record heads have about 0.5-1 GOhm to pin 13. Are they gone or do I need to measure to another reference pin?”

Thank you.

Around 24 minutes there is a short explanation (In French).

Thank you!

I can’t understand French but the video is very informative. I landed on his web page from the video. There are a couple interesting articles there and a link to a French forum with some information about DCC in general and capacitor problem in particular. Very interesting indeed.

All my recording heads have 3.1Ohm, so It looks like they are fine.
ICs have no broken internal diodes, so I will test now all board voltages.

You can measure voltage on the tape head pins during stop, the should be about 650 mV. Another thing to check are the voltages on the read amplifier input pins (about 540 mV) and on the output pin and on the both output transistors.

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I will check it out.
Thank you for the suggestion.